96 lines
3.0 KiB
C++
96 lines
3.0 KiB
C++
#include "./mpeg4descriptor.h"
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#include "./mp4container.h"
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#include "./mp4ids.h"
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#include <c++utilities/conversion/stringbuilder.h>
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#include <c++utilities/conversion/stringconversion.h>
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#include <c++utilities/io/binaryreader.h>
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using namespace std;
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using namespace CppUtilities;
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namespace TagParser {
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/*!
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* \class TagParser::Mpeg4Descriptor
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* \brief The Mpeg4Descriptor class helps to parse MPEG-4 descriptors.
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*/
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/*!
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* \brief Constructs a new top level descriptor with the specified \a container at the specified \a startOffset
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* and with the specified \a maxSize.
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*/
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Mpeg4Descriptor::Mpeg4Descriptor(ContainerType &container, std::uint64_t startOffset, std::uint64_t maxSize)
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: GenericFileElement<Mpeg4Descriptor>(container, startOffset, maxSize)
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{
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}
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/*!
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* \brief Constructs a new sub level descriptor with the specified \a parent at the specified \a startOffset.
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*/
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Mpeg4Descriptor::Mpeg4Descriptor(Mpeg4Descriptor &parent, std::uint64_t startOffset)
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: GenericFileElement<Mpeg4Descriptor>(parent, startOffset)
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{
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}
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/*!
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* \brief Returns the parsing context.
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*/
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string Mpeg4Descriptor::parsingContext() const
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{
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return "parsing " % idToString() % " descriptor at " + startOffset();
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}
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/*!
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* \brief Converts the specified atom \a ID to a printable string.
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*/
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std::string Mpeg4Descriptor::idToString() const
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{
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return "0x" + numberToString(id(), 16);
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}
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/*!
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* \brief Parses the MPEG-4 descriptor.
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* \remarks Does not detect the first child.
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*/
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void Mpeg4Descriptor::internalParse(Diagnostics &diag)
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{
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if (maxTotalSize() < minimumElementSize()) {
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diag.emplace_back(DiagLevel::Critical,
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"Descriptor is smaller than 2 byte and hence invalid. The maximum size within the encloding element is " % numberToString(maxTotalSize())
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+ '.',
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"parsing MPEG-4 descriptor");
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throw TruncatedDataException();
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}
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stream().seekg(static_cast<streamoff>(startOffset()));
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// read ID
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m_idLength = m_sizeLength = 1;
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m_id = reader().readByte();
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// read data size
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std::uint8_t tmp = reader().readByte();
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m_dataSize = tmp & 0x7F;
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while (tmp & 0x80) {
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m_dataSize = (m_dataSize << 7) | ((tmp = reader().readByte()) & 0x7F);
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++m_sizeLength;
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}
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// check whether the denoted data size exceeds the available data size
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if (maxTotalSize() < totalSize()) {
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diag.emplace_back(DiagLevel::Warning, "The descriptor seems to be truncated; unable to parse siblings of that ", parsingContext());
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m_dataSize = static_cast<std::uint32_t>(maxTotalSize()); // using max size instead
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}
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m_firstChild.reset();
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// check for siblings
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if (totalSize() >= maxTotalSize()) {
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m_nextSibling.reset();
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return;
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}
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if (parent()) {
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m_nextSibling.reset(new Mpeg4Descriptor(*(parent()), startOffset() + totalSize()));
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} else {
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m_nextSibling.reset(new Mpeg4Descriptor(container(), startOffset() + totalSize(), maxTotalSize() - totalSize()));
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}
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}
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} // namespace TagParser
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